This application claims the benefit of Japanese Patent Application No. 2004-30804, filed Feb. 6, 2004, which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a stacking-type, multi-flow, heat exchanger comprising an end plate connected to an outermost layer of a heat exchanger core formed by stacking heat transfer tubes and fins alternately, and to methods for manufacturing such heat exchangers. Specifically, the present invention relates to an improved structure of a stacking-type, multi-flow, heat exchanger suitable as a heat exchanger for use in an air conditioner, in particular, for vehicles.
2. Description Related Art
A stacking-type, multi-flow, heat exchanger having alternately stacked heat transfer tubes and fins is known in the art, for example, as a heat exchanger having a structure shown in FIGS. 22 and 23 (as shown in Japanese Utility Model Laid-Open No. 7-12778). In FIGS. 22 and 23, a heat exchanger 101 has a heat exchanger core 104 formed by heat transfer tubes 102 and fins 103 i.e., (outer fins) stacked alternately. A side tank 105 is provided on one end of heat exchanger core 104 in the stacking direction, for forming introduction/discharge passages of a heat exchange medium (e.g., refrigerant), and a flange 106 connected with an expansion valve (not shown) is connected to side tank 105. On the other end of heat exchanger core 104, an end plate 107 is provided.
Each heat transfer tube 102 is formed by connecting (e.g., brazing) a pair of tube plates 108, which have the same configuration, to each other. Projecting portions 109 and 110 are provided on both ends of each tube plate 108 for forming tanks 111 and 112 at the upper and lower portions of heat exchanger core 104. Communication holes 113 and 114 for a heat exchange medium are formed through projecting portions 109 and 110. To form heat transfer tube 102, a pair of tube plates 108 are connected to each other, so that the respective projecting portions 109 and 110 are set at opposite sides, and projecting portions 109 and projecting portions 110 of a plurality of heat transfer tubes 102 are connected to each other, respectively, to form tanks 111 and 112 at either end of heat exchanger core 104. Communication holes 113 and 114 of outermost tube plate 108 at the end plate side are closed by projecting portions 115 and 116 of end plate 107, respectively.
Heat exchanger 101 may be manufactured by temporarily assembling the respective members, and brazing the assembly at a later time in a furnace, wherein the assembly is held from both sides of heat exchanger 101 in the stacking direction by a brazing jig (not shown).
In such a manufacturing method, however, because projecting portions 109 and 110 of heat transfer tubes 102, and projecting portion 109 (110) of outermost tube plate 108 and projecting portion 115 (116) of end plate 107, are assembled, such that they are in surface contact, a positional shift may occur when assembled or during brazing in a furnace. Consequently, the respective parts may not be connected properly.
To solve such a problem, Japanese Published Patent Application No. JP-A-5-87482 proposes the following structure, as depicted in FIG. 24. In this structure, each heat transfer tube 117 is formed by a first tube plate 118 and a second tube plate 119. A raised portion 122 is formed by creating a lip or edge on a projecting portion 121 for forming a tank of second tube plate 119, and raised portion 122 is inserted into a communication hole 123 formed through a projecting portion 120 of first tube plate 118 to prevent a positional shift at the time of the assembly. An opening 126 of raised portion 122 of outermost tube plate 119 is closed by a projecting portion 125 of an end plate 124.
In such a structure, however, because it is difficult to ensure a sufficiently large area for brazing between projecting portion 125 of end plate 124 and raised portion 122 of projecting portion 121 of outermost tube plate 119, insufficient brazing strength may be achieved. Further, because it is difficult to temporarily fix end plate 124 to outermost tube plate 119 with a high degree of accuracy when assembled, the brazing accuracy may be reduced.